[ars]

> Apparently there are 100, of which you consumed 0.

The 100 is a normalized number, it's not the actual number of blocks. (A percentage basically, so 100% are still left.)

If the drive used any blocks at all I'd worry about it, I would not consider it a wear indicator but rather a failure indicator.

[jmpe]

> The 100 is a normalized number, it's not the actual number of blocks.

I'm not too sure about that. The only ref I can give is that they use the suffix "Cnt_Tot" which means "total count". When it's a percentage they denote it as such as in "Perc_Rated_Life_Used" and "Workld_Host_Reads_Perc". Don't be surprised by the low count (100).

[yuriks]

That's how SMART attributes work. 100 means AOK and 0 means failed. The normalized number is reported by the drive, calculated by a formula based off the raw values and MTBF data determined by the manufacturer.

[jmpe]

Ok, dug around in the code.

In Smartmontools I found the code for this variable:

http://smartmontools.sourceforge.net/doxygen/atacmds_8cpp_so...

It's code 179 (0xB3).

From Samsung's website:

http://www.samsung.com/global/business/semiconductor/minisit...

  ID # 179 Used Reserved Block Count (total)

  This attribute represents the number of reserved blocks that have been used as a result of a read, program or erase failure. This value is related to attribute 5 (Reallocated Sector Count) and will vary based on SSD density.

.. so at least for samsung there's use of exact numbers.

From Intel's website:

http://download.intel.com/newsroom/kits/ssd/pdfs/intel_ssd_5...

(Ctrl-F for "Available Reserved Space")

.. they use a normalized value (100).

So it can be either percentage or absolute value, depending on manufacturer.